To increase battery life of wireless station, a power save mode is defined in many wireless network protocols. In IEEE 802.11 networks, a wireless station is either in a receive state in which it is listening for frames, a transmit state in which it is sending frames, or a power save mode in which it is neither transmitting nor receiving. This causes a very large portion of wireless stations to be powered-up most of time. The wireless station in power save mode consumes much less power by shutting off power to nearly everything except for a timing circuit. This enables the wireless station to consume very little power and wake up periodically (in multiples of beacon intervals) to receive beacon transmissions from an access point.
Paging is a wireless service for alerting a wireless station in a power save mode to the arrival of frames and optionally to buffer arrived frames until the paged station wakes up and receives them. The area in which paging is used is referred to as a paging area. A paging area boundary is defined by the outer perimeter of the ranges of a collection of access points (an “access point group”) that are used to locate a dormant wireless station. This outer perimeter forms the paging area boundary of a paging area. Each paging area uniquely identifies itself to wireless stations by periodically broadcasting its unique paging area identifier. Although many cellular-based wireless WAN protocols support paging, WLAN protocols, such as the IEEE 802.11, do not specifically provide standards or methods for implementing paging. For example, the IEEE 802.11 protocol does not have paging areas with more than one access point, a dedicated paging channel and a radio link protocol specifically directed towards locating a dormant wireless station that is in a power save mode.
Some wireless networks, such as IEEE 802.11, have inflexible paging architecture. In IEEE 802.11, paging area consists of single access point, so wireless station should perform location registration whenever it enters coverage area of new AP. As wireless stations become more mobile, power consumption caused by inflexible paging architecture becomes more significant.